import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int age;
        age = in.nextInt();
        Person p = new Person(age);
        age = in.nextInt();
        try {
            p.setAge(age);
        } catch (Exception e) {
            System.out.println("B");
            return;
        }
        System.out.println("A");
    }
}

class Person {
    int age;

    public Person(int age) {
        this.age = age;
    }

    public void setAge(int age) throws AgeException {
        if (this.age <= age) {
            this.age = age;
        } else {
            throw new AgeException();
        }

    }
}

class AgeException extends Exception {
    // 自定义异常类
}